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Bela oceanic lithosphere assemblage and its relation to the Réunion hotspot
Author(s) -
Edwin Gnos,
Muhammad Anees Khan,
Khalid Mahmood,
Abdul Salam Khan,
Naseer A. Shafigue,
Igor M. Villa
Publication year - 1998
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1046/j.1365-3121.1998.00173.x
Subject(s) - ophiolite , geology , obduction , accretionary wedge , geochemistry , subduction , continental margin , foreland basin , oceanic crust , petrology , paleontology , structural basin , tectonics
The Bela ophiolite of Pakistan contains a complete ophiolite‐accretionary wedge‐trench sequence emplaced onto the Indian continental margin during the northward drift of India‐Seychelles over the active Réunion hotspot. A structurally higher ophiolite overlies an accretionary prism, which is thrust over a foreland basin. Shear‐sense determinations in peridotite mylonites in the ophiolite footwall and imbrication structures in the underlying accretionary wedge indicate an ESE emplacement. Sedimentary rocks in the accretionary wedge indicate Aptian‐Albian pillow lavas, initially deep water conditions, and increasing influence from the continent until the Maastrichtian. The ophiolite emplacement was predated and accompanied by Fe‐tholeiitic and alkaline magmatism related to the Réunion hotspot and continuous incorporation of trench sediments into the accretionary wedge. 39 Ar/ 40 Ar dating shows that the ophiolite formed around 70 Ma. Intraoceanic subduction initiated between 70 and 65 Ma, obduction onto the Indian passive margin occurred during the formation of the Deccan traps at ≈ 66 Ma, and final thrusting onto the continental margin ended in the early Eocene (≈ 50 Ma). The ophiolite emplacement occurred during the counterclockwise separation of Madagascar and India‐Seychelles which caused shortening and consumption of oceanic lithosphere between the African‐Arabian and the Indian‐Seychelles plates.